Microbicidal composition

ABSTRACT

A synergistic microbicidal composition having two components. The first component is a nonionic surfactant with structure: R 2 O(CH 2 CH(CH 3 )O) 3 (CH 2 CH 2 O) 7 H, where R 2  is a mixture of C 8 -C 14  linear alkyl groups. The second component is tris(hydroxymethyl)nitromethane. The weight ratio of the nonionic surfactant to tris(hydroxymethyl)nitromethane is from 1:0.16 to 1:1.8286.

This invention relates to microbicidal compositions containing cis-1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride (CTAC), 4,4-dimethyloxazolidine (DMO) or tris(hydroxymethyl)nitromethane (Tris Nitro) and a surfactant.

A composition containing 5-chloro-2-methylisothiazolin-3-one, 2-methylisothiazolin-3-one and a nonionic dispersant is disclosed in U.S. Pat. No. 4,295,932. The composition contains a 3:1 mixture of 5-chloro-2-methylisothiazolin-3-one and 2-methylisothiazolin-3-one, and a copolymer of ethylene oxide and propylene oxide which appears to have the same composition as PLURONIC L61 or TERGITOL L61 dispersant. However, there is a need for combinations of microbicides having synergistic activity against various strains of microorganisms to provide effective control of the microorganisms. Moreover, there is a need for such combinations containing lower levels of individual microbicides for environmental and economic benefit. The problem addressed by this invention is to provide such synergistic combinations of microbicides.

STATEMENT OF THE INVENTION

The present invention is directed to a synergistic microbicidal composition comprising: (a) a nonionic surfactant with structure:

-   -   R¹O(CH₂CH(CH₃)O)₅(CH₂CH₂O)₉H         where R¹ is a C₈ alkyl group; and (b)         cis-1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride;         wherein a weight ratio of said nonionic surfactant to         cis-1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride         is from 1:0.2 to 1:1.1429.

The present invention is further directed to a synergistic microbicidal composition comprising: (a) a nonionic surfactant with structure:

-   -   R²O(CH₂CH(CH₃)O)₃(CH₂CH₂O)₅H         where R² is a mixture of C₈-C₁₄ linear alkyl groups; and (b)         cis-1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride;         wherein a weight ratio of said nonionic surfactant to         cis-1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride         is from 1:0.04 to 1:0.9143.

The present invention is further directed to a synergistic microbicidal composition comprising: (a) a nonionic surfactant with structure:

-   -   R²O(CH₂CH(CH₃)O)₃(CH₂CH₂O)₇H         where R² is a mixture of C₈-C₁₄ linear alkyl groups; and (b)         cis-1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride;         wherein a weight ratio of said nonionic surfactant to         cis-1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride         is from 1:0.016 to 1:0.0571.

The present invention is further directed to a synergistic microbicidal composition comprising: (a) a nonionic surfactant with structure:

-   -   R¹O(CH₂CH(CH₃)O)₅(CH₂CH₂O)₉H         where R¹ is a C₈ alkyl group; and (b) 4,4-dimethyloxazolidine;         wherein a weight ratio of said nonionic surfactant to         4,4-dimethyloxazolidine is from 1:0.0286 to 1:0.1143 or 1:0.32         to 1:0.9143.

The present invention is further directed to a synergistic microbicidal composition comprising: (a) a nonionic surfactant with structure:

-   -   R²O(CH₂CH(CH₃)O)₃(CH₂CH₂O)₅H         where R² is a mixture of C₈-C₁₄ linear alkyl groups; and (b)         4,4-dimethyloxazolidine; wherein a weight ratio of said nonionic         surfactant to 4,4-dimethyloxazolidine is from 1:0.06 to         1:0.6857.

The present invention is further directed to a synergistic microbicidal composition comprising: (a) a nonionic surfactant with structure:

-   -   R²O(CH₂CH(CH₃)O)₃(CH₂CH₂O)₇H         where R² is a mixture of C₈-C₁₄ linear alkyl groups; and (b)         4,4-dimethyloxazolidine; wherein a weight ratio of said nonionic         surfactant to 4,4-dimethyloxazolidine is from 1:0.024 to         1:0.2743.

The present invention is further directed to a synergistic microbicidal composition comprising: (a) a nonionic surfactant with structure:

-   -   R²O(CH₂CH(CH₃)O)₃(CH₂CH₂O)₇H         where R² is a mixture of C₈-C₁₄ linear alkyl groups; and (b)         tris(hydroxymethyl)nitromethane; wherein a weight ratio of said         nonionic surfactant to tris(hydroxymethyl)nitromethane is from         1:0.16 to 1:1.8286.

The present invention is further directed to methods for inhibiting the growth of microorganisms in aqueous media by adding to an aqueous medium a nonionic surfactant as described herein and cis-1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride, 4,4-dimethyloxazolidne or tris(hydroxymethyl)nitromethane in the ratios described herein.

DETAILED DESCRIPTION OF THE INVENTION

“CTAC” is cis-1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride, CAS No. 51229-78-8, “DMO” is 4,4-dimethyloxazolidine, CAS No. 51200-87-4, and “Tris Nitro” is tris(hydroxymethyl)nitromethane, CAS No. 126-11-4. As used herein, the following terms have the designated definitions, unless the context clearly indicates otherwise. The term “microbicide” refers to a compound capable of inhibiting the growth of or controlling the growth of microorganisms; microbicides include bactericides, fungicides and algaecides. The term “microorganism” includes, for example, fungi (such as yeast and mold), bacteria and algae. The following abbreviations are used throughout the specification: ppm=parts per million by weight (weight/weight), mL=milliliter. Unless otherwise specified, temperatures are in degrees centigrade (° C.), references to percentages are percentages by weight (wt %) and amounts and ratios are on an active ingredient basis, i.e., total weight of CTAC and the nonionic surfactant. Numbers of polymerized units of propylene oxide or ethylene oxide are number averages.

Preferably, the weight ratio of the nonionic surfactant with structure:

-   -   R¹O(CH₂CH(CH₃)O)₅(CH₂CH₂O)₉H         where R¹ is a C₈ alkyl group to CTAC is from 1:0.2857 to         1:1.1429, preferably from 1:0.5714 to 1:1.1429. Preferably, the         weight ratio of the nonionic surfactant with structure:     -   R²O(CH₂CH(CH₃)O)₃(CH₂CH₂O)₅H         where R² is a mixture of C₈-C₁₄ linear alkyl groups to CTAC is         from 1:0.0457 to 1:0.9143.

The present invention is further directed to a method for inhibiting the growth of S. aureus, in an aqueous medium by adding: (a) a nonionic surfactant with structure:

-   -   R²O(CH₂CH(CH₃)O)₃(CH₂CH₂O)₅H         where R² is a mixture of C₈-C₁₄ linear alkyl groups; and (b)         CTAC; wherein a weight ratio of said nonionic surfactant to CTAC         is from 1:0.0457 to 1:0.9143.

The present invention is further directed to a method for inhibiting the growth of S. aureus, in an aqueous medium by adding: (a) a nonionic surfactant with structure:

-   -   R²O(CH₂CH(CH₃)O)₃(CH₂CH₂O)₇H         where R² is a mixture of C₈-C₁₄ linear alkyl groups; and (b)         Tris Nitro; wherein a weight ratio of said nonionic surfactant         to Tris Nitro is from 1:0.16 to 1:1.8286.

R² is a mixture of C₈-C₁₄ linear alkyl groups. Preferably, the C₈-C₁₄ linear alkyl groups comprise from 50 to 85 wt % C₈-C₁₀ linear alkyl groups and 15 to 50 wt % C₁₂-C₁₄ linear alkyl groups, preferably from 60 to 75 wt % C₈-C₁₀ linear alkyl groups and 25 to 40 wt % C₁₂-C₁₄ linear alkyl groups, preferably about 70 wt % C₈-C₁₀ linear alkyl groups and about 30 wt % C₁₂-C₁₄ linear alkyl groups. Preferably, the linear alkyl groups are derived from seed oil. Preferably, R¹ is 2-ethylhexyl.

Preferably, each of the compositions is substantially free of microbicides other than the nonionic surfactant and CTAC, DMO or Tris Nitro, i.e., it has less than 1 wt % of microbicides other than the nonionic surfactant and CTAC, DMO or Tris Nitro based on total weight of active ingredients, preferably less than 0.5 wt %, preferably less than 0.2 wt %, preferably less than 0.1 wt %. Preferably, when the nonionic surfactant and CTAC, DMO or Tris Nitro are added to an aqueous medium, the medium is substantially free of other microbicides, i.e., it has less than 1 wt % of microbicides other than the nonionic surfactant and CTAC, DMO or Tris Nitro based on total weight of active ingredients, preferably less than 0.5 wt %, preferably less than 0.2 wt %, preferably less than 0.1 wt %.

The compositions of this invention may contain other ingredients, e.g., defoamers and emulsifiers. The microbicidal compositions of the present invention can be used to inhibit the growth of microorganisms or higher forms of aquatic life (such as protozoans, invertebrates, bryozoans, dinoflagellates, crustaceans, mollusks, etc) by introducing a microbicidally effective amount of the compositions into an aqueous medium subject to microbial attack. Suitable aqueous media are found in, for example: industrial process water; electrocoat deposition systems; cooling towers; air washers; gas scrubbers; mineral slurries; wastewater treatment; ornamental fountains; reverse osmosis filtration; ultrafiltration; ballast water; evaporative condensers; heat exchangers; pulp and paper processing fluids and additives; starch; plastics; emulsions; dispersions; paints; latices; coatings, such as varnishes; construction products, such as mastics, caulks, and sealants; construction adhesives, such as ceramic adhesives, carpet backing adhesives, and laminating adhesives; industrial or consumer adhesives; photographic chemicals; printing fluids; household products, such as bathroom and kitchen cleaners; cosmetics; toiletries; shampoos; soaps; personal care products such as wipes, lotions, sunscreen, conditioners, creams, and other leave-on applications; detergents; industrial cleaners; floor polishes; laundry rinse water; metalworking fluids; conveyor lubricants; hydraulic fluids; leather and leather products; textiles; textile products; wood and wood products, such as plywood, chipboard, flakeboard, laminated beams, oriented strandboard, hardboard, and particleboard; petroleum processing fluids; fuel; oilfield fluids, such as injection water, fracture fluids, and drilling muds; agriculture adjuvant preservation; surfactant preservation; medical devices; diagnostic reagent preservation; food preservation, such as plastic or paper food wrap; food, beverage, and industrial process pasteurizers; toilet bowls; recreational water; pools; and spas.

The specific amount of the microbicidal compositions of this invention necessary to inhibit or control the growth of microorganisms in an application will vary. Typically, the amount of the composition of the present invention is sufficient to control the growth of microorganisms if it provides from 300 to 10,000 ppm (parts per million) active ingredients of the composition. It is preferred that the active ingredients (i.e., nonionic surfactant and CTAC, DMO or Tris Nitro) of the composition be present in the medium to be treated in an amount of at least 500 ppm, preferably at least 600 ppm, preferably at least 800 ppm. It is preferred that the active ingredients of the composition be present in the locus in an amount of no more than 6,000 ppm, preferably no more than 5,000 ppm, preferably no more than 4,000 ppm, preferably no more than 3,000 ppm, preferably no more than 2,500 ppm, preferably no more than 2,000 ppm. In a method of this invention, a composition is treated to inhibit microbial growth by adding, together or separately, the nonionic surfactant and CTAC, DMO or Tris Nitro, in amounts that would produce the concentrations indicated above.

EXAMPLES

Surfactants and biocides were evaluated for synergy by determining the synergy index (S.I.) of the combination. Synergy index was calculated based on minimum inhibitory concentrations (MIC) of two antimicrobial compounds (A and B) alone and in combinations. The tests organisms were Gram negative bacteria (Pseudomonas aeruginosa ATCC #15442), Gram positive bacteria (Staphylococcus aureus ATCC #6538), yeast (Candida albicans ATCC#10203) and mold (Aspergillus niger ATCC#16404). Contact time for the bacteria was 24 and 48 hours, yeast was 48 and 72 hrs, and 3 and 7 days for mold. The test was carried out in 96 well microtiter plates.

-   Surf. A R¹O(CH₂CH(CH₃)O)₅(CH₂CH₂O)₉H, where R¹ is 2-ethylhexyl -   Surf. D R²O(CH₂CH(CH₃)O)₃(CH₂CH₂O)₅H -   Surf. E R²O(CH₂CH(CH₃)O)₃(CH₂CH₂O)₇H -   In Surf. D and Surf. E, R² is a mixture of C₈-C₁₄ linear alkyl     groups (70% C₈-C₁₀ linear alkyl and 30% C₁₂-C₁₄ linear alkyl)

Inoculums Used Inoculum Size of organisms (CFU/ml) Staphylococcus Pseudomonas Aspergillus Candida aureus aeruginosa niger albicans Surfactants ATCC# 6538 ATCC # 15442 ATCC# 16404 ATCC#10203 Surf. A 1.156E+06 8.134E+07 1.156E+06 1.156 + 06 Surf. D 1.808E+05 1.156E+08 1.156E+06 5.726E+05 Surf. E 1.808E+06 5.727E+07 5.726E+05 1.808E+06

TABLE 4 Media Used Media Used for testing Staphylococcus Pseudomonas Aspergillus Candida aureus aeruginosa niger albicans ATCC# 6538 ATCC # 15442 ATCC# 16404 ATCC#10203 10% Tryptic soy 10% Tryptic soy Potato dextrose Potato dextrose broth broth broth broth

The pH of the Triptic soy broth was 7.3 and the Potato dextrose broth was 5.1.

The test results for demonstration of synergy of the MIC combinations are shown in the tables below. Each table shows the results for combinations of two components against the microorganisms tested with incubation times; the end-point activity in ppm measured by the MIC for compound A alone (CA), for component B alone (CB), and the mixture (Ca) and (Cb); the calculated SI value; and the range of synergistic ratios for each combination tested. SI is calculated as follows: Ca/CA+Cb/CB=Synergy Index(“SI”)

Wherein:

-   -   CA=concentration of compound A in ppm, acting alone, which         produced an end point (MIC of Compound A).     -   Ca=concentration of compound A in ppm, in the mixture, which         produced an end point.     -   CB=concentration of compound B in ppm, acting alone, which         produced an end point (MIC of Compound B).     -   Cb=concentration of compound B in ppm, in the mixture, which         produced an end point.

When the sum of Ca/CA and Cb/CB is greater than one, antagonism is indicated. When the sum is equal to one, additivity is indicated, and when less than one, synergism is demonstrated.

The ratio ranges at which CTAC, DMO or Tris Nitro and the surfactants were tested are as summarized in the following tables:

CTAC with Surf. A Organism ATCC# From To Ratio Range Staphylococcus 6538 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 aureus Aspergillus 16404 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 niger Candida 10203 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 albicans Pseudomonas 15442 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 aeruginosa

CTAC with Surf. E Organism ATCC# From To Ratio Range Staphylococcus aureus 6538 0.2:20,000  1,000:218.75 1:0.00001-1:4.5714 Aspergillus niger 16404 2.0:20,000 10,000:218.75  1:0.0001-1:45.7143 Candida albicans 10203 2.0:20,000 10,000:218.75  1:0.0001-1:45.7143 Pseudomonas aeruginosa 15442 0.2:20,000  1,000:218.75 1:0.00001-1:4.5714

CTAC with Surf. D Organism ATCC# From To Ratio Range Staphylococcus aureus 6538 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Aspergillus niger 16404 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Candida albicans 10203 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Pseudomonas aeruginosa 15442 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714

DMO with Surf. A Organism ATCC# From To Ratio Range Staphylococcus aureus 6538 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Aspergillus niger 16404 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Candida albicans 10203 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Pseudomonas aeruginosa 15442 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714

DMO with Surf. E Organism ATCC# From To Ratio Range Staphylococcus aureus 6538 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Aspergillus niger 16404 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Candida albicans 10203 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Pseudomonas aeruginosa 15442 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714

DMO with Surf. D Organism ATCC# From To Ratio Range Staphylococcus aureus 6538 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Aspergillus niger 16404 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Candida albicans 10203 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Pseudomonas aeruginosa 15442 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714

TrisNitro with Surf. A Organism ATCC# From To Ratio Range Staphylococcus aureus 6538 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Aspergillus niger 16404 0.02:20,000    100:218.75 1:0.000001-1:0.45714 Candida albicans 10203 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Pseudomonas aeruginosa 15442 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714

TrisNitro with Surf. E Organism ATCC# From To Ratio Range Staphylococcus aureus 6538 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Aspergillus niger 16404 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Candida albicans 10203 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Pseudomonas aeruginosa 15442 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714

TrisNitro with Surf. D Organism ATCC# From To Ratio Range Staphylococcus aureus 6538 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Aspergillus niger 16404 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Candida albicans 10203 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714 Pseudomonas aeruginosa 15442 0.2:20,000 1,000:218.75 1:0.00001-1:4.5714

-   A: Surf. A -   B: CTAC -   Media: PDB -   Inoculum size: 1.156E+06

A. niger ATCC#16404 No Synergy C. albicans ATCC#10203 No Synergy

-   A: Surf. A -   B: CTAC -   Media: 1/10 TSB -   Inoculum size: 1.156E+06

S. aureus ATCC#6538 No Synergy

-   A: Surf. A -   B: CTAC -   Media: 1/10 TSB -   Inoculum size: 1.156E+06

PPM AI MIC Values (3^(rd) Day) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) P. aeruginosa >20000 600 20000 500 <1.83 1:0.0250 ATCC#15442 >20000 600 10000 500 <1.33 1:0.0500 >20000 600 5000 500 <1.08 1:0.1000 >20000 600 2500 500 <0.96 1:0.2000 >20000 600 1750 500 <0.92 1:0.2857 >20000 600 875 500 <0.88 1:0.5714 >20000 600 437.5 500 <0.86 1:1.1429

-   A: Surf. D -   B: CTAC -   Media: PDB -   Inoculum size: 1.156E+06

PPM AI MIC Values (3rd day) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) A. niger >20000 1000 10000 600 <1.10 1:0.0600 >20000 1000 10000 800 <1.30 1:0.0800 ATCC#16404 >20000 1000 5000 800 <1.05 1:0.1600 >20000 1000 2500 800 <0.93 1:0.3200 >20000 1000 1750 800 <0.89 1:0.4571 >20000 1000 875 800 <0.84 1:0.9143

-   A: Surf. D -   B: CTAC -   Media: PDB -   Inoculum size: 5.726E+05 CFU/ml

PPM AI MIC Values (48 hrs) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) C. albicans >20000 1000 10000 400 <0.90 1:0.0400 ATCC#10203 >20000 1000 10000 500 <1.00 1:0.0500 >20000 1000 10000 600 <1.10 1:0.0600 >20000 1000 10000 800 <1.30 1:0.0800 >20000 1000 5000 400 <0.65 1:0.0800 >20000 1000 5000 500 <0.75 1:0.1000 >20000 1000 5000 600 <0.85 1:0.1200 >20000 1000 5000 800 <1.05 1:0.1600

-   A: Surf. D -   B: CTAC -   Media: 1/10 TSB -   Inoculum size: 1.808E+05

PPM AI MIC Values (24 hrs) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) S. aureus >20000 300 10000 80 <0.77 1:0.0080 ATCC# 6538 >20000 300 10000 100 <0.83 1:0.0100 >20000 300 10000 200 <1.17 1:0.0200 >20000 300 5000 200 <0.92 1:0.0400 >20000 300 5000 80 <0.52 1:0.0160 >20000 300 5000 100 <0.58 1:0.0200 >20000 300 1750 80 <0.35 1:0.0457 >20000 300 1750 100 <0.42 1:0.0571 >20000 300 1750 200 <0.75 1:0.1143 >20000 300 875 200 <0.71 1:0.2286 >20000 300 437.5 200 <0.69 1:0.9143 >20000 300 218.75 200 <0.68 1:0.2286

-   A: Surf. D -   B: CTAC -   Media: 1/10 TSB -   Inoculum size: 1.156E+06

P. aeruginosa ATCC#15442 No Synergy

-   A: Surf. E -   B: CTAC -   Media: PDB -   Inoculum 1.808E+05

A. niger ATCC 16404 No synergy

-   A: Surf. E -   B: CTAC -   Media: PDB -   Inoculum 1.808E+05

PPM AI MIC Values (48 hrs) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) C. albicans >20000 2997 10000 1999 <1.17 1:0.1999 ATCC 10203

-   A: Surf. E -   B: CTAC -   Media: 1/10 TSB -   Inoculum size: 5.72E+07

P. aeruginosa ATCC#15442 No synergy

-   A: Surf. E -   B: CTAC -   Media: 1/10 TSB -   Inoculum size: 1.8E+06

PPM AI MIC Values (24 hrs) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) S. aureus >20000 200 10000 80 <0.90 1:0.0080 ATCC# 6538 >20000 200 10000 100 <1.00 1:0.0100 >20000 200 5000 80 <0.65 1:0.0160 >20000 200 5000 100 <0.75 1:0.0200 >20000 200 2500 100 <0.63 1:0.0400 >20000 200 1750 100 <0.59 1:0.0571

-   A: Surf. A -   B: Tris Nitro -   No synergy: -   S. aureus, A. niger, C. albicans, Ps. aeruginosa -   A: Surf. D -   B: TrisNitro -   Media: 1/10 TSB -   Inoculum size: 1.16E+08

PPM AI MIC Values (24 hrs) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) Ps. aeruginosa >20000 800 20000 1000 <2.25 1:0.0500 ATCC#15442 >20000 800 10000 1000 <1.75 1:0.1000 >20000 800 5000 1000 <1.50 1:0.2000 >20000 800 2500 800 <1.13 1:0.3200 >20000 800 1750 1000 <1.34 1:0.5714 >20000 800 875 800 <1.04 1:0.9143 >20000 800 437.5 600 <0.77 1:1.3714 >20000 800 437.5 800 <1.02 1:1.8286 >20000 800 218.75 800 <1.01 1:3.6571

-   No synergy: S. aureus, A. niger, C. albicans -   A: Surf. E -   B: TrisNitro -   Media: 1/10 TSB -   Inoculum size: 5.727E+07 CFU/ml

PPM AI MIC Values (24 hrs) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) Ps. aeruginosa >20000 1000 20000 1000 <2.00 1:0.0500 ATCC#15442 >20000 1000 10000 1000 <1.50 1:0.1000 >20000 1000 5000 1000 <1.25 1:0.2000 >20000 1000 2500 1000 <1.13 1:0.4000 >20000 1000 1750 1000 <1.09 1:0.5714 >20000 1000 875 1000 <1.04 1:1.1429 >20000 1000 437.5 800 <0.82 1:1.8286 >20000 1000 437.5 1000 <1.02 1:2.2857 >20000 1000 218.75 800 <0.81 1:3.6571 >20000 1000 218.75 1000 <1.01 1:4.5714

-   A: Surf. E -   B: TrisNitro -   Media: 1/10 TSB -   Inoculumsize: 1.808E+06 CFU/ml

PPM AI MIC Values (24 hrs) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) S. aureus >20000 500 20000 500 <2.00 1:0.0250 ATCC# 6538 >20000 500 10000 400 <1.30 1:0.0400 >20000 500 5000 400 <1.05 1:0.0800 >20000 500 2500 400 <0.93 1:0.1600 >20000 500 1750 300 <0.69 1:0.1714 >20000 500 1750 400 <0.89 1:0.2286 >20000 500 875 400 <0.84 1:0.4571 >20000 500 437.5 400 <0.82 1:0.9143 >20000 500 218.75 400 <0.81 1:1.8286 >20000 500 218.75 500 <1.01 1:2.2857

-   No synergy: A. niger, C. albicans -   A: Surf. A -   B: DMO -   Media: PDB -   Inoculum size: 1.156E+06 CFU/ml

PPM AI MIC Values (3^(rd) Day) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) A. niger >20000 60 10000 50 <1.33 1:0.0050 ATCC#16404 >20000 60 5000 50 <1.08 1:0.0100 >20000 60 2500 50 <0.96 1:0.0200 >20000 60 1750 50 <0.92 1:0.0286 >20000 60 875 50 <0.88 1:0.0571 >20000 60 437.5 50 <0.86 1:0.1143

-   A: Surf. A -   B: DMO -   Media: PDB -   Inoculum size: 1.156E+06 CFU/ml

PPM AI MIC Values (3^(rd) Day) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) C. albicans >20000 1000 10000 800 <1.30 1:0.0800 ATCC#10231 >20000 1000 5000 800 <1.05 1:0.1600 >20000 1000 2500 800 <0.93 1:0.3200 >20000 1000 875 800 <0.84 1:0.9143

-   A: Surf. A -   B: DMO -   Media: 1/10 TSB -   Inoculum size: 8.134+07 CFU/ml

PPM AI MIC Values (24 hrs) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) P. aeruginosa >20000 80 20000 60 <1.75 1:0.0030 ATCC#15442

-   A: Surf. A -   B: DMO -   Media: 1/10 TSB -   Inoculum size: 1.156E+06 CFU/ml

PPM AI MIC Values (24 hrs) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) S. aureua >20000 50 20000 40 <1.80 1:0.0020 ATCC#6538

-   A: Surf. D -   B: DMO -   Media: 1/10 TSB -   Inoculum size: 1.16E+08

P. aeruginosa ATCC#15442 No Synergy

-   A: Surf. D -   B: DMO -   Media: PDB -   Inoculum size: 1.156E+06

PPM AI MIC Values (3rd day) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) A. niger >20000 400 10000 300 <1.25 1:0.0300 ATCC# 16404 >20000 400 5000 300 <1.0 1:0.0600 >20000 400 437.5 300 <0.77 1:0.6857

-   A: Surf. D -   B: DMO -   Media: PDB -   Inoculum size: 5.726E -   +05 CFU/ml

PPM AI MIC Values (48 hrs) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) C. albicans >20000 1000 10000 800 <1.30 1:0.0800 ATCC#10231 >20000 1000 5000 800 <1.05 1:0.1600

-   A: Surf. D -   B: 1135 -   Media: 1/10 TSB -   Inoculum size: 1.16E+08

PPM AI MIC Values (24 hrs) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) S. aureus >20000 80 10000 50 >1.13 1:0.0050 ATCC#6538 >20000 80 10000 60 >1.25 1:0.0060 >20000 80 5000 50 <0.88 1:0.0100 >20000 80 5000 60 <1.00 1:0.0025 >20000 80 2500 60 <0.88 1:0.0120 >20000 80 1750 50 <0.71 1:0.0240 >20000 80 1750 60 <0.84 1:0.0286 >20000 80 875 50 <0.67 1:0.0343 >20000 80 875 60 <0.79 1:0.0571 >20000 80 437.5 50 <0.65 1:0.0686 >20000 80 437.5 60 <0.77 1:0.1143 >20000 80 218.75 60 <0.76 1:0.1371

-   A: Surf. E -   B: DMO -   Media: PDB -   Inoculum size: 1808E+06

PPM AI MIC Values (48 hrs) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) C. albicans >20000 1000 10000 600 <1.10 1:0.0600 ATCC#10203 >20000 1000 10000 800 <1.30 1:0.0800 >20000 1000 5000 600 <0.85 1:0.1200 >20000 1000 5000 800 <1.05 1:0.1600

-   A: Surf. E -   B: DMO -   Media: PDB

P. aeruginosa ATCC#15442 No Synergy

-   A: Surf. E -   B: DMO -   Media: PDB -   Inoculum size: 1.56E+06 CFU/ml

PPM AI MIC Values (3^(rd) Day) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) A. niger >20000 800 10000 600 <1.25 1:0.0600 ATCC#16404 >20000 800 5000 600 <1.00 1:0.1200 >20000 800 437.5 600 <0.77 1:1.3714

-   A: Surf. E -   B: DMO -   Media: 1/10 TSB -   Inoculum size: 1.80E+06 CFU/ml

PPM AI MIC Values (24 hrs) Test Alone Combination Ratio Organism CA CB Ca Cb S.I. (Ca:Cb) ATCC# 6538 >20000 80 10000 50 <1.13 1:0.0050 >20000 80 10000 60 <1.25 1:0.0060 >20000 80 5000 50 <0.88 1:0.0100 >20000 80 5000 60 <1.00 1:0.0120 >20000 80 2500 60 <0.88 1:0.0240 >20000 80 1750 60 <0.84 1:0.0343 >20000 80 875 60 <0.79 1:0.0686 >20000 80 437.5 50 <0.65 1:0.1143 >20000 80 437.5 60 <0.77 1:0.1371 >20000 80 218.75 60 <0.76 1:0.2743

The following biocides had no synergy against any organism tested when paired with the following surfactants:

-   Surf. A -   Sodium Benzoate, TRIS NITRO -   Surf. E -   DMDMH -   Surf. D -   CS-1246, OPP, DMDMH

In the following combinations, the ratio of surfactant to biocide where synergy was observed were not commercially relevant, i.e., a ratio of 1:0.2 or greater (less biocide relative to surfactant). At these ratios, the biocide levels in a formulated product would be too low to be practical:

-   Surf. A -   DIDAC, IPBC -   Surf. E -   CMIT/MIT, IPBC, OIT, TTPC, WSCP -   Surf. D -   CMIT/MIT, OIT, DIDAC -   (MBIT, IPBC, WSCP were synergistic only at 1:0.05 or worse except     for one data point). 

The invention claimed is:
 1. A synergistic microbicidal composition comprising: (a) a nonionic surfactant with structure: R²O(CH₂CH(CH₃)O)₃(CH₂CH₂O)₇H where R² is a mixture of C₈-C₁₄ linear alkyl groups; and (b) tris(hydroxymethyl)nitromethane; wherein a weight ratio of said nonionic surfactant to tris(hydroxymethyl)nitromethane is from 1:0.16 to 1:1.8286; and wherein said mixture of C₈-C₁₄ linear alkyl groups comprises from 60 to 75 wt % C₈-₁₀ linear alkyl groups and 25 to 40 wt % C₁₂-C₁₄ linear alkyl groups. 